Reduction of silver ores.



COLIN G. FINK, 0F SCHENECTADY, NEW YORK, COMPANY, A CORPORATION assreivon i0 GENERAL nnncrnrc or new YORK.

REDUCTION 'OF SILVER ORES.

ItTo Drawing.

I Specification of Letters Patent. Application filed December 4, 1908.

Patented Jan. a, rare. Serial No. 465,932.

To all whom it may concern: Be it known that I, COLIN G. F INK, a citi- .zen of the United States, residing at Schecounty of Scl1enectady, State of nectady, New York, have invented certain new and useful Improvements in Reduction of Silver Ores, of which the following is specification. My invention relates to the treatment of silver ores containing arsenic or antimony, together with other metallic elements which render very diliicult the refining of these ores according to processes formerly in use. For example, if an ore ofthis character is subjected to a preliminary, open air roasting process, in order to removethe arsenic, a considerable amount of silver is lost by being volatilized with the arsenic. According to my. invention, the yield in silver is not only increased; but an easy separation of the silver from the other metallic constituents of the ore, such as cobalt, nickel and iron, is obtained. I have discovered that when this class of ores are heated to the fusing temperature, either in an attenuated atmosphere or a reducing atmosphere, the greater part of the arsenic, or antimony, as the case may be, is distilled oil" as metallic arsenic or antimony, and the melted ore stratifies into three distinct layers: the lowermost layer being nearly pure silver with a small percentage of arsenic the middle layer a speiss containing cobalt, nickel and iron, and the uppermost layer a slag, consisting chiefly of calcium silicate.

My process is especially apQicableto the Nipissing silver ores from the region of Co balt, Canada. A sample of this ore was found on analysis to contain 9.7% cobalt, 4.65% nickel, 28.65% arsenic, 18.06% silver; the remaining 39% consisting of iron, aluminum, calcium, silicon, antimony, and perhaps other elements.

The ore is preferably ground so as to pass through a forty mesh sieve. In some cases carbon in the form of cokeor charcoal is added to facilitate its decomposition. The amount of carbon added depends 'on the character of the ore. For instance, if oxide are present in consider-able amount, more coke is added for their reduction. Its act-ion ispartly chemical, as a reducing agent, and partly physical, in so' far as it keeps the charge porous, thus allowing the gases to escape readily. Should the gangue admixed three hours.

with the ore be refractory, and its melting point be above or even near, the melting point of silver, fluxes are perfectly added. Their choice, of course, depends on the character ofthe gangue, a basic flux being added if the gangue is acidic, or the reverse, as is Well understood by metallurgists. The charge is placed in a graphite or carbon crucible, oris introduced into a treating chamber through a hopper. If the ore is to be subjected to a vacuum treatment, the crucible filled with ore is placed in a furnace of the general principle of the Arsem furnace described in The vacuum treatment 1s preferable, as the arsenic off at a lower temperature than when heating the ore at atmospheric pressures. If desired, the orecan be heated in a reducing atmosphere, such as carbon monoxid gas or other reducing gas. A good separation can bebbtained in this way-at atmospheric pressure. In either case the ore is heated to a temperature of 1.2004500 (I, and heating maintained at this temperature for two or By this treatment a greater part of the arsenic is volatilized as metallic arsenic, and. the Stratification of the fused ore into crude silver, speiss, and slag takes place, as already indicated. The volatilized arsenic passes out to chamber.

If the ore has been heated'in a crucible in a vacuum furnace, the furnace is allowed to cool down sufficiently to enable the removal of the crucible with its charge from the furnace. If desired,'the silver maybe mechanically separated 3 from the speiss when solidified, ,or, the charge may be tapped oft-while melted, the silver being separated by regation. The metallic silver is then subin some respects may be distilled iecte'd to further treatment for the'removal' of-the impurities present, consisting of'iron, nickel, cobalt, and traces of arsenic. This maybe done by distilling the silver from the impurities in a vacuum, furnace of the Arsem type. The speiss may be subjected to further purification according to methods now in use,' soas to remove the remaining arsenic and separate the metals as nickel and cobalt from each other.

What I claim as new and desire to secure by Letters Patent of the United States, is,

Patent No. 785,535 of 1905'.

a suitable condensing 1. The process of treating ores containing silver and arsenic, which consists infusing thereby. causing segregation into distinct said ores in an attenuated atmosphere, layers of respectively crude silver, a speiss thereby distilling on the arsenic and allowcontaining cobalt and nickel and a slag. ingthe silver to separate from the slag by 5. The process which consistsin heating gravity. a silver ore containing a metalloid in an 2. The process of treating a silver-bearing inert environment at a temperature high arsenic ore, which consists in heating said enough to volatilize a large part of said ore to fusing temperature in a vacuum and metalloid and maintaining the residue or maintaining said ore fused until the crude said ore in a state of fusion to produce segsilver separates by, gravity. I regation of the crude silver from the rest of 3. The process of separating substantially the mass. pure silver from an arsenical silver ore 6. The process which consists in heating which consists in fusing said ore out of'conan arsenical sllver ore In an inert environtact with the atmosphere, distilling part ment thereby volatilizing arsenic and mainof the arsenic, and allowing the silver to taining the residue in a state of fusion to segregate from the rest of the charge while assist the segregation of the crude silver the charge is maintained fused. from the rest of the reduction mass.

4:. The process of treating an ore contain- In witness whereof, I have hereunto set ing silver, cobalt, nickel, a metalloid and my hand this 1st day of December, 1908. earthy impurities which consists in heating COLIN Gr. FTNK. said ore 1n an inert environment, thereby Witnesses: vaporizing most of the metalloid, and main- BENJAMIN B. "HULL,

taining the residue in astate of fusion HELEN OREORD. 

